This invention relates to a method and apparatus for reducing the thickness of metal strip. The invention is applicable to a wide range of metals and alloys which are capable of plastic deformation. The apparatus comprises a biased cooperative rolling mill which is adapted to provide increased reduction in thickness of the metal strip per pass as well as increased total reduction between anneals as compared to various prior art approaches. The biasing of the mill enables control of the magnitude of, for example, the final reduction taken in each pass through the mill.